Frequency noise reduction performance of a feed-forward heterodyne technique: application to an actively mode-locked laser diode

Abstract

We report on the frequency noise reduction performance of a feed-forward technique. The Letter is based on frequency noise measurements that allow the spectral response of the feed-forward phase noise correction to be determined. The main limitation to the noise compensation is attributed to the local oscillator flicker noise and the noise added by the optoelectronic loop elements. The technique is applied to an actively mode-locked laser diode demonstrating, at the output of the system, an optical frequency comb source with 14 comb lines reduced to sub-kilohertz intrinsic linewidth.

Phase Noise Effects on Phase-Sensitive OTDR Sensors Using Optical Pulse Compression

“…where E(t) is a periodic complex function representing the PPA or the LFM modulations, ω 0 is the center radial frequency and φ(t) represents the laser's phase noise. The stochastic properties of φ(t) and their characterization, in narrow-linewidth laser sources, have been studied extensively in recent years [17], [18], [19], [20], [21], [22]. While these properties differ significantly from one type of laser to another, it is generally accepted that φ(t) can be modeled as a sum of terms, each with a different Power Spectral Density (PSD).…”